Typography is the art and technique of arranging type to make written language legible, readable, and appealing when displayed. The arrangement of type involves selecting typefaces, point sizes, line lengths, line-spacing (leading), and letter-spacing (tracking), and adjusting the space between pairs of letters (kerning). The term typography is also applied to the style, arrangement, and appearance of the letters, numbers, and symbols created by the process. Type design is a closely related craft, sometimes considered part of typography; most typographers do not design typefaces, and some type designers do not consider themselves typographers. Typography also may be used as a decorative device, unrelated to communication of information.
A typeface is a collection of letters. While each letter is unique, certain shapes are shared across letters. A typeface represents shared patterns across a collection of letters.
Also Known As: counter. In typography, a counter or aperture is an area entirely or partially enclosed by a letter form or a symbol (the counter-space/ the hole of). Letters containing closed counters include A, B, D, O, P, Q, R, a, b, d, e, g, o, p, and q.
Ascenders are an upward vertical stroke found in certain lowercase letters that extend beyond either the cap height or baseline. Descenders are the downward vertical stroke in these letters. In some cases, a collision between these strokes can occur when the line height (the vertical distance between baselines) is too tight.
The baseline is the invisible line upon which a line of text rests.
Cap height refers to the height of a typeface’s flat capital letters (such as M or I) measured from the baseline. Round and pointed capital letters, such as S and A, are optically adjusted by being drawn with a slight overshoot above the cap height to achieve the effect of being the same size. Every typeface has a unique cap height.
Line lengths for body text are usually between 40 to 60 characters. In areas with wider line lengths, such as desktop, longer lines that contain up to 120 characters will need an increased line height from 20sp to 24sp.
Line height, also known as leading, controls the amount of space between baselines in a block of text. A text’s line height is proportional to its type size.
Letter-spacing, also called tracking, refers to the uniform adjustment of the space between letters in a piece of text. Larger type sizes, such as headlines, use tighter letter-spacing to improve readability. For smaller type sizes, looser letter spacing can improve readability as more space between letters increases contrast between each letter shape. Text in all caps, even at small type sizes, has improved readability because of its added letter spacing.
The stem is the main, usually vertical stroke of a letterform. Also Known As: stroke. A main or heavy stroke of a letter.
The main diagonal portion of a letterform such as in N, M, or Y is the stroke. The stroke is secondary to the main stem(s). Some letterforms with two diagonals, such as A or V have a stem (the primary vertical or near-vertical stroke) and a stroke (the main diagonal).
Type alignment controls how text aligns in the space it appears. There are three type alignments: left-aligned, right-aligned, and centered.
X-height refers to the height of the lowercase x for a typeface, and it indicates how tall or short each glyph in a typeface will be. Typefaces with tall x-heights have better legibility at small font sizes, as the white space within each letter is more legible. The height of a typeface’s lower-case x determines its x-height.
Weight refers to the relative thickness of a font’s stroke. A typeface can come in many weights; and four to six weights is a typical number available for a typeface.